add logging on fetch & cache; add mechanism to bypass cache

inc/http-client/class-cache-strategy.php

@@ -2,18 +2,56 @@
 
 namespace RemoteDataBlocks\HttpClient;
 
-use Kevinrob\GuzzleCache\KeyValueHttpHeader;
-use Kevinrob\GuzzleCache\Storage\CacheStorageInterface;
 use Kevinrob\GuzzleCache\Strategy\GreedyCacheStrategy;
+use Psr\Http\Message\RequestInterface;
 use RemoteDataBlocks\Logging\LoggerManager;
 
 class CacheStrategy extends GreedyCacheStrategy {
-	const HEADER_TTL = 'X-RemoteDataBlocks-TTL';
+	const HEADER_TTL          = 'X-RemoteDataBlocks-TTL';
+	const HEADER_BYPASS_CACHE = 'X-RemoteDataBlocks-Bypass-Cache';
 
-	protected $logger;
+	private static function getRequestString( RequestInterface $request ) {
+		$uri        = $request->getUri();
+		$uri_string = $uri->getScheme() . '://' . $uri->getHost() . $uri->getPath();
+		$method     = $request->getMethod();
+		$body       = $request->getBody()->getContents();
+		return $method . ' ' . $uri_string . ' ' . $body;
+	}
+
+	protected function should_bypass_cache( RequestInterface $request ) {
+		$bypass = $request->getHeader( self::HEADER_BYPASS_CACHE );
+		if ( ! empty( $bypass ) ) {
+			return true;
+		}
+
+		return false;
+	}
+
+	public function fetch( RequestInterface $request ) {
+		$logger = LoggerManager::instance();
+
+		if ( $this->should_bypass_cache( $request ) ) {
+			$logger->debug( 'Bypassing cache: ' . self::getRequestString( $request ) );
+			return null;
+		}
+
+		$result = parent::fetch( $request );
+
+		if ( null === $result ) {
+			$logger->debug( 'Cache Miss: ' . self::getRequestString( $request ) );
+			return null;
+		}
+		$logger->debug( 'Cache Hit: ' . self::getRequestString( $request ) );
+		return $result;
+	}
 
-	public function __construct( CacheStorageInterface $cache = null, $default_ttl, KeyValueHttpHeader $vary_headers = null ) {
-		$this->logger = LoggerManager::instance();
-		parent::__construct( $cache, $default_ttl, $vary_headers );
+	public function cache( RequestInterface $request, $response ) {
+		$result = parent::cache( $request, $response );
+		$logger = LoggerManager::instance();
+		if ( false === $result ) {
+			$logger->debug( 'Did not cache: ' . self::getRequestString( $request ) );
+			return false;
+		}
+		$logger->debug( 'Cached: ' . self::getRequestString( $request ) );
 	}
 }